Thousands of green recycling bins were slapped with yellow stickers to show they would not be emptied after being found to contain the wrong items.
Officers – dubbed "binspectors" – travelled with crews to check residents' bins for the wrong items, such as food, household waste and black bags.
The move has proved controversial with residents and sparked a flurry of complaints, with some claiming they felt penalised for trying to recycle.
Sean Coughlan, deputy leader of Walsall's Labour group, said: "We find it really disappointing the council has allowed it to get to this stage.
"As local councillors we're all picking up complaints from our most vulnerable residents, who in many cases are the more elderly people."
Council chiefs say the zero-tolerance crackdown was introduced after increasing amounts of "contaminated" waste had to be sent to landfill, costing taxpayers money.
Figures from the first two weeks of the operation show more than 11,000 of the borough's 100,000 households fell foul of the crackdown.
Tom Ansell, environment chief, said: "We now have two weeks of data on recycling collections since November 19.
"This tells us that an overwhelming majority of 89 per cent of residents are recycling properly.
"Every item improperly recycled effectively costs the taxpayer money which is why we are being diligent and residents can help us to do this."
Yvonne Preston, of Skip Lane, was one of the thousands of residents who did not have their bin collected.
The married 53-year-old today said she was still not entirely sure what incorrect item had been placed in her bin, making it difficult for her to sort out the problem.
She added: "I'm worried because there is a problem with fly-tipping at the end of Skip Lane and I'm worried people will come and just start dumping their bags of rubbish here."
Mrs Preston also said passers-by could dump the 'wrong' rubbish in people's bins.